Defect-engineered hierarchical NH2-MIL-101(Fe) for enhanced Au(III) adsorption through pore channel regulation

Efficient recovery of Au(III) from electronic and industrial waste streams is of both economic and environmental importance. Herein, a pore-regulation strategy was developed to construct hierarchically porous NH 2 -MIL-101(Fe 1-x Cu x ). By employing 2-aminoterephthalic acid to coordinate simultaneously with Fe 3 + and Cu 2+ , the unstable Cu–O bonds were selectively removed through a mild acid-soaking treatment, thereby generating enlarged channels and hierarchical micro–mesoporous structures. The optimized framework achieved an Au(III) adsorption capacity of 944 mg g −1 , which was ∼30.7 % higher than that of unmodified NH 2 -MIL-101. Mechanistic studies demonstrated that the hierarchical pore architecture not only facilitated mass transfer but also enhanced accessibility of active sites, synergistically contributing to the superior adsorption performance. This work highlights that rational pore-channel engineering around adsorption sites can substantially boost the recovery efficiency of reducible precious metals, offering a novel design paradigm for advanced MOF-based adsorbents.